code: def test_Observation(self) -> None:
      obs = Observation(
          features=ObservationFeatures(parameters={"x": 20}),
          data=ObservationData(
              means=np.array([1]),
              covariance=np.array([[2]]),
              metric_names=["a"],
          ),
          arm_name="0_0",
      )
      self.assertEqual(
          obs.features, ObservationFeatures(parameters={"x": 20})
      )
      self.assertEqual(
          obs.data,
          ObservationData(
              means=np.array([1]),
              covariance=np.array([[2]]),
              metric_names=["a"],
          ),
      )
      self.assertEqual(obs.arm_name, "0_0")
      obs2 = Observation(
          features=ObservationFeatures(parameters={"x": 20}),
          data=ObservationData(
              means=np.array([1]),
              covariance=np.array([[2]]),
              metric_names=["a"],
          ),
          arm_name="0_0",
      )
      self.assertEqual(obs, obs2)
      obs3 = Observation(
          features=ObservationFeatures(parameters={"x": 10}),
          data=ObservationData(
              means=np.array([1]),
              covariance=np.array([[2]]),
              metric_names=["a"],
          ),
          arm_name="0_0",
      )
      self.assertNotEqual(obs, obs3)
      self.assertNotEqual(obs, 1)
  
imports: import json
  from unittest.mock import Mock, PropertyMock
  import numpy
  import pandas
  from ax.core.arm import Arm
  from ax.core.base_trial import TrialStatus
  from ax.core.batch_trial import BatchTrial
  from ax.core.data import Data
  from ax.core.generator_run import GeneratorRun
  from ax.core.map_data import MapData, MapKeyInfo
  from ax.core.observation import Observation, ObservationData, ObservationFeatures, observations_from_data, observations_from_map_data, recombine_observations, separate_observations
  from ax.core.trial import Trial
  from ax.utils.common.testutils import TestCase
label_desc: Use image node_id 8 for calling the ObservationsTest obj's underlying member method code with example usage: obj.test_Observation() without return types